1. Field of the Invention
This invention generally relates to pneumatic actuators, and more specifically, relates to an apparatus and method for indicating movement of a pneumatic actuator.
2. Background Art
Pneumatic actuators are very cost effective actuators, and are found in many applications, such as manufacturing, aerospace, and commercial vehicles. Generally, in the operation of, for example, a linear pneumatic actuator, a high-pressure fluid is conducted to the actuator to extend or retract a piston. Movement of the piston may then be used to actuate some other mechanism such as a switch or valve.
Currently, at least in many specific applications, there is no available method to indicate the movement of a pneumatic actuator other than a visual observation through a window located on the actuator body. This feature, though, cannot be used if the actuator is in a very inaccessible area. Also, the window cannot be read from a long distance.
For example, pneumatic actuators are used in sheet making processes to control the amount of steam applied to the formed sheets. In this application, the pneumatic actuator may be mounted on a beam in a relatively inaccessible location and operated from a remote distance. As a result, any window on the actuator body is inaccessible and too far away from the operator to be used to see movement of the actuator. Moreover, the actuator may be enclosed in a protective dust cover, which makes it even more difficult to observe movement of the actuator.